Recently, many surgical devices have been made flexible for use in endoscopic procedures, allowing the devices to be inserted through a working channel of an endoscope. The ability to grasp tissue, apply fasteners, or perform various other procedures through an endoscope permits myriad minimally invasive surgical solutions to medical problems, especially those of the gastrointestinal tract.
Some endoscopic surgical devices include a flexible tubular shaft, a control member longitudinally movable relative to the tubular shaft, an end effector coupled to the distal ends of the tubular member and the control member, and a housing with controls for actuating the control member. Actuation of the control member relative to the tubular member causes operation of the end effector, which can be, for example, a pair of opposed tissue-effecting jaws. Some devices are also configured such that rotation of the control member can be effective to rotate the end effector.
One drawback of current endoscopic surgical devices resides in the difficulty to rotate the end effector. As mentioned above, rotation of a control member can rotate the end effector. This can be achieved by applying torque to the distal end of the tubular shaft to thereby rotate the shaft and thus rotate the end effector coupled thereto. For example, a knob coupled to the proximal end of the control member can be rotated to rotate the control member, and thereby rotate the tubular shaft and end effector. The knob is rotationally coupled to the control member and is allowed to freewheel; that is, the knob spins freely, providing minimal rotational resistance. Often, multiple turns of the knob are necessary to rotate the end effector a desired amount, as the rotation angle of the knob is greater than the corresponding rotation of the end effector because of the angular deformation of the control member due to its relatively long length and small diameter and also due to the torsional resistances provided by the shaft. When the user rotates the knob, the control member twists until the resistance torque is overcome, eventually causing the tubular shaft to rotate and thereby rotate the end effector. However, release of the knob between turns would allow the control member to un-twist, driving itself and the knob, as the knob is rotationally coupled to the control member and provides little rotational resistance, to a neutral energy state (state of zero or near zero angular deflection). As a result, the user must keep at least a finger on the knob to prevent the control member from unwinding as they impart successive rotations to the knob. This can be difficult to achieve comfortably and with only one hand, which is often necessary during surgical procedures.
Accordingly, there remains a need for improved methods and devices for rotating an end effector on an endoscopic surgical device.